Dishwashers, such as those found in many homes, provide a washing chamber holding one or more racks sized to support eating utensils and cookware for cleaning. The washing chamber may be sealed by a door opening at the front of the washing chamber to allow loading and unloading of the chamber. The door is closed during a washing cycle to prevent the escape of water sprayed within the volume of the washing chamber during the washing of items placed in the racks. Upon completion of the washing cycle, a drying cycle is initiated during which water is drained from the washing chamber and moist air is discharged through a vent. Cool air, pulled by convection or by a fan into the chamber through a lower vent, flows upward, augmented by natural convection to dry the heated dishes.
Recent dishwasher designs may employ a one-piece tub, for example of stainless steel, which defines the washing chamber and, when closed by the door, is sealed from communication with the outside air. The sealed nature of this chamber makes the promotion of air circulation for proper venting particularly difficult.
U.S. Pat. No. 7,887,643 entitled: “Dishwasher With Counter-Convection Air Flow”, assigned to the same assignee as the present invention and hereby fully incorporated by reference, describes a downdraft venting system in which low-turbulence down-flow is created within the washing chamber to more efficiently remove moisture-laden air from the washing chamber and dishes. In one embodiment, a relatively small fan placed at the top of the washing chamber draws dry air into the washing chamber to push moist air out of existing vents near the bottom of the washing machine door.
The greater efficiency of this downdraft design in removing moisture from the washing chamber and contained dishes can create condensation problems when high humidity air is exhausted from the dishwasher and contacts cool surfaces, such as a metal-faced dishwasher door. This condensation may cause the undesirable collection of water on surfaces near the vent outlet.
U.S. Pat. No. 7,909,939, entitled: “Humidity Reducing Exhaust Duct for Dishwasher”, assigned to the same assignee as the present invention and hereby fully incorporated by reference, describes an exhaust duct designed to handle the higher humidity air provided by more efficient low turbulence down-flow venting or the like. The duct provides a mixing chamber to mix cool dry air with the warm humid air and a reservoir for accumulating condensation before exit from the duct into the environment around the dishwasher. This reservoir may be dried by continued fan operation after the venting is complete.
Clothes washing machines, and in particular water-saving, front-loading washing machines, may provide a sealed door preventing the escape of water during the washing cycle. If this door is closed after completion of the washing cycle and removal of the washed clothes, residual humidity can be trapped in the washing chamber, risking the growth of mold or the generation of musty odors.